Method for recycling neodymium oxide by using neodymium iron boron permanent magnet material in waste motor

Abstract

The invention provides a method for recovering neodymium oxide by using a neodymium-iron-boron permanent magnet material in a waste motor, which comprises the following steps of: firstly, decomposing the neodymium-iron-boron permanent magnet material in the waste motor into a fine particle raw material through a combined process of pre-cleaning, roasting and demagnetizing, twice crushing and screening, so that the subsequent acid dissolution contact area can be increased, and the yield of neodymium oxide is increased; the subsequent acid dissolution difficulty is simplified, the acid consumption and the reaction time are reduced, and the acid consumption cost is reduced, so that the dissolution efficiency of rare earth elements (such as neodymium) is improved; meanwhile, according to the method, reverse extraction is conducted on the organic extraction liquid through a synergistic reverse extraction agent composed of oxalic acid and sulfuric acid, the sulfuric acid can help to wash the organic phase to be recycled, the oxalic acid can reversely extract the organic phase to directly form neodymium oxalate sediment, and therefore the leaching cost of the neodymium iron boron original material is reduced, and the recovery process is simplified; and the recovery efficiency of neodymium oxide is finally improved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste recycling, in particular to a method for recycling neodymium oxide by utilizing neodymium iron boron permanent magnet materials in waste motors. Background Art

[0002] Neodymium iron boron (NdFeB) permanent magnets, due to their excellent magnetic properties, are widely used in next-generation information technology, variable-frequency air conditioning, rail transportation, new energy vehicles, and wind power generation. Since the invention of third-generation NdFeB permanent magnets, they have been recognized as the "king of permanent magnets" for their high remanence, high coercivity, and high magnetic energy product. According to the Statistical Review of World Energy 2024, global rare earth mineral reserves and production will reach 115.602 million tons and 353,670 tons, respectively, in 2023. China will lead the world in both rare earth mineral reserves and production, at 44 million tons and 240,000 tons, respectively, accounting for 38.1% and 67.9% of the global share. According to data from the China Economic Industry Research Institute, rare earth permanent magnets accounted for over 40% of China's rare earth consumption in 2022, far exceeding other sectors. Other major application areas, such as smelting machinery, petrochemicals, and glass and ceramics, will account for 13%, 9%, and 8%, respectively. The market demand for NdFeB permanent magnet materials is strong, which has prompted researchers to devote themselves to the research of NdFeB permanent magnet material properties and new magnetic materials.

[0003] The Chinese invention patent "A method for preparing high-performance and high-coercivity regenerated sintered NdFeB magnets using waste permanent magnet motor magnets" has an application publication number of CN104036946A. This invention uses rare earth praseodymium hydride nanopowder doping technology to regenerate waste rare earth permanent magnet motor magnets to prepare high-performance sintered NdFeB permanent magnets. This invention has a long invention cycle. The Chinese invention patent "Method for recovering rare earths from NdFeB waste by high-temperature and high-pressure leaching" has an application publication number of CN109554549B. It discloses a method for recovering rare earths from NdFeB waste by high-temperature and high-pressure leaching. This invention involves oxidizing and roasting NdFeB waste, leaching with hydrochloric acid at high temperature and high pressure, and removing Fe in the leachate. 2+ The leaching solution is then oxidized and purified to produce a rare earth chloride leachate. This rare earth chloride leachate can be used as a raw material for subsequent processes and products, such as extracting and separating rare earths, preparing rare earth carbonates through precipitation, or preparing rare earth oxides through precipitation and roasting. Although acid consumption is reduced, the acid leaching process requires a relatively high amount of acid, and a large amount of alkali is required for neutralization during treatment.

[0004] Therefore, it is of great practical significance to develop an efficient, environmentally friendly, low-cost and easy-to-industrialize method for recovering neodymium from NdFeB permanent magnet materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for recovering neodymium oxide using neodymium iron boron permanent magnet materials in waste motors, so as to improve the technical problems of the existing methods for recovering neodymium oxide, such as low recovery rate, high cost, high pollution and complex process, and realize the efficient and environmentally friendly recovery of neodymium iron boron permanent magnet materials in waste motors, improve resource utilization and reduce the impact on the environment.

[0006] To solve the above technical problems, the present invention provides a method for recovering neodymium oxide from NdFeB permanent magnet materials in waste motors, comprising: S10, pre-cleaning, roasting and demagnetizing, primary crushing, high-temperature roasting and secondary crushing of the waste motor in sequence, and obtaining NdFeB raw material after filtering and screening; S20, performing acid dissolution treatment on the NdFeB raw material, and obtaining rare earth solution and iron oxide after solid-liquid separation; S30, extracting the rare earth solution to obtain an iron-containing raffinate and an organic extract; S40, stripping the organic extract with a synergistic stripping agent to obtain a stripping solution and a regenerated organic raffinate, wherein the synergistic stripping agent includes oxalic acid and sulfuric acid; S50, sequentially precipitating, washing, filtering and calcining the stripping solution to obtain neodymium oxide.

[0007] Preferably, the calcination temperature for calcination and demagnetization in step S10 is 300-400° C., and the holding time is 1-3 hours; or, the calcination temperature for calcination and demagnetization in step S10 is 200-300° C., and the holding time is 10-20 hours.

[0008] Preferably, in step S10, the high-temperature calcination temperature is 300-500° C., and the holding time is 2-4 hours.

[0009] Preferably, in step S20, the NdFeB raw material is subjected to acid dissolution treatment by water bath heating, and the water bath heating temperature of the water bath heating method is 50-80°C.

[0010] Preferably, in step S20, the acid added in the acid dissolution treatment includes at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and the acid concentration is 2-6 mol / L.

[0011] Preferably, in step S30, the rare earth solution is extracted with an extractant, and the extractant includes at least one of a P507 reagent, a P204 reagent, a TBP reagent, and a C272 reagent.

[0012] Preferably, in step S40, the molar ratio of oxalic acid to sulfuric acid in the synergistic stripping agent is (0.5-1):1.

[0013] Preferably, in step S40, the O / A ratio after the synergistic stripping agent and the organic extract are mixed is between 2:1 and 1:2.

[0014] Preferably, in step S50, the step of performing precipitation treatment on the stripping solution comprises: adding excess oxalic acid to the stripping solution, mixing and stirring at 70-90° C. for 40-80 minutes to obtain neodymium oxalate precipitate.

[0015] Preferably, in step S50, the step of calcining the neodymium oxalate precipitate includes: calcining the neodymium oxalate precipitate at 700-900° C. and keeping the temperature for 1-3 hours.

[0016] The beneficial effects of the present invention are as follows: different from the prior art, the present invention provides a method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors, comprising: first, pre-cleaning, roasting and demagnetizing, primary crushing, high-temperature roasting and secondary crushing of the waste motors in sequence, filtering and screening to obtain NdFeB raw materials; secondly, acid-dissolving the NdFeB raw materials, and obtaining rare earth solution and iron oxide after solid-liquid separation; then, extracting the rare earth solution to obtain iron-containing raffinate and organic extract; then, stripping the organic extract with a synergistic stripping agent to obtain a stripping solution and a regenerated organic raffinate, wherein the synergistic stripping agent includes oxalic acid and sulfuric acid; finally, precipitating and treating the stripping solution in sequence Washing, filtering and roasting are performed to obtain neodymium oxide. The present invention first decomposes the NdFeB permanent magnet material in the waste motor into fine-grained raw materials through a combined process of pre-cleaning → roasting and demagnetization → two crushings → screening, which can increase the contact area of ​​subsequent acid dissolution, simplify the difficulty of subsequent acid dissolution, reduce the amount of acid used and the reaction time, and reduce the acid consumption cost, thereby improving the dissolution efficiency of rare earth elements (such as neodymium). At the same time, the method uses a synergistic stripping agent composed of oxalic acid and sulfuric acid to strip the organic extract. Sulfuric acid can help wash the organic phase and then recycle it, and oxalic acid can strip the organic phase to directly form a neodymium oxalate precipitate, thereby reducing the leaching cost of the NdFeB raw material and simplifying the recovery process, and ultimately improving the recovery efficiency of neodymium oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a method for recovering neodymium oxide using NdFeB permanent magnet materials from waste motors provided in an embodiment of the present invention; Figure 2 This is a process flow chart of the method for recovering neodymium oxide using neodymium iron boron permanent magnet materials in waste motors provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] The purpose of the present invention is to overcome the above-mentioned technical deficiencies and provide a method for recovering neodymium oxide from NdFeB permanent magnet materials in waste motors by using a high-efficiency stripping agent. The method aims to solve the problems of low recovery rate, high cost, high pollution and complex process in existing recovery methods, and realize efficient and environmentally friendly recovery of NdFeB permanent magnet materials in waste motors, improve resource utilization and reduce the impact on the environment.

[0020] See also Figure 1 , Figure 1 A flow chart of a method for recovering neodymium oxide from NdFeB permanent magnets in waste motors provided by an embodiment of the present invention; wherein the method for recovering neodymium oxide from NdFeB permanent magnets in waste motors specifically includes: S10, pre-cleaning, roasting and demagnetizing, primary crushing, high-temperature roasting and secondary crushing are sequentially performed on the waste motor, and NdFeB raw materials are obtained after filtering and screening.

[0021] Specifically, step S10 further includes: First, a scrap motor is provided, and the magnetic steel in the scrap motor is pre-cleaned: the scrap motor is disassembled and the magnetic steel is taken out, the plating and impurities are removed, and the magnetic steel is cleaned to obtain clean scrap motor magnetic steel for standby use.

[0022] Secondly, the cleaned scrap motor magnets are subjected to roasting and demagnetization treatment; the roasting temperature for roasting and demagnetization is 300~400℃, and the holding time is 1~3h; or, the roasting temperature for roasting and demagnetization is 200~300℃, and the holding time is 10~20h; among them, since the scrap motor magnets themselves are magnetic and difficult to crush, the scrap motor magnets need to be roasted and demagnetized before the first crushing treatment.

[0023] Next, the demagnetized scrap motor magnetic steel is crushed (mechanically crushed) to obtain coarse magnetic steel.

[0024] Next, the crude magnetic steel is subjected to high-temperature calcination, wherein the calcination temperature is 300-500° C. and the holding time is 2-4 hours. The purpose of the high-temperature calcination is to destroy the physical structure of the crude magnetic steel.

[0025] Finally, the coarse magnetic steel after high-temperature roasting is subjected to secondary crushing (mechanical crushing) to obtain fine-grained magnetic steel, which is then sieved through a filter to obtain NdFeB raw material. Among them, the coarse magnetic steel after high-temperature roasting is prone to agglomeration and requires secondary crushing.

[0026] S20, performing acid dissolution treatment on the NdFeB raw material, and obtaining rare earth solution and iron oxide after solid-liquid separation.

[0027] Specifically, step S20 further includes: First, the NdFeB raw material is mixed with acid for acid dissolution treatment by water bath heating. At this time, the NdFeB raw material is preferentially dissolved in the acid solution. The acid added in the acid dissolution treatment includes at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and the acid concentration is 2~6 mol / L. The water bath heating temperature of the bath heating method is 50~80℃.

[0028] Specifically, water bath heating conducts heat through the aqueous medium, ensuring uniform temperature distribution across the reaction system. This prevents localized excessive acid concentrations during acid dissolution, leading to violent reactions (such as splashing and the release of large amounts of acid mist), and improves operational safety. Precise temperature control between 50°C and 80°C ensures the acid dissolution reaction rate while preventing acid decomposition (such as increased nitric acid volatilization) or rare earth hydrolysis and precipitation at high temperatures, maintaining efficient dissolution efficiency.

[0029] Secondly, the mixed solution obtained by acid leaching is subjected to solid-liquid separation treatment (filtration) to obtain a Nd rare earth solution and waste residue (iron oxide).

[0030] S30, extracting the rare earth solution to obtain an iron-containing raffinate and an organic extract.

[0031] Specifically, step S30 further includes: The rare earth solution is extracted with an extractant to obtain an iron-containing raffinate and an organic extract. The iron-containing raffinate can be used to recover a ferric chloride solution. The extractant includes at least one of a P507 reagent (2-ethylhexyl phosphate), a P204 reagent (di(2-ethylhexyl) phosphate), a TBP reagent (tributyl phosphate), and a C272 reagent (di(2,4,4-trimethylpentyl)phosphinic acid).

[0032] This step separates rare earth and iron by extraction, achieving rare earth enrichment in the organic phase, while iron and some impurities remain in the aqueous phase, and recovering ferric chloride solution from the raffinate (which can be recycled as an industrial raw material) S40, stripping the organic extract with a synergistic stripping agent to obtain a stripping solution and a regenerated organic raffinate, wherein the synergistic stripping agent includes oxalic acid and sulfuric acid.

[0033] Specifically, step S40 further includes: First, a synergistic stripping agent composed of oxalic acid and sulfuric acid is prepared, wherein the molar ratio of oxalic acid to sulfuric acid in the synergistic stripping agent is (0.5-1):1.

[0034] Secondly, the organic extract containing rare earth elements is stripped with a synergistic stripping agent to obtain a stripping solution containing rare earth elements and a regenerated organic raffinate containing the extractant; the O / A value (volume ratio of the organic phase to the aqueous phase) after the synergistic stripping agent and the organic extract are mixed is between 2:1 and 1:2.

[0035] Specifically, oxalic acid acts as a strong complexing agent, and oxalate ions form a stable oxalate rare earth precipitate with rare earth ions, destroying the complexing equilibrium between rare earth and the extractant in step S30, and promoting the transfer of rare earth from the organic phase to the aqueous phase. Sulfuric acid can inhibit the excessive dissociation of oxalic acid and ensure that there is sufficient H + , reducing the acidic dissociation of extractants (such as P507 reagent) and preventing them from competing with rare earth elements for binding. Furthermore, the sulfate ions provided by sulfuric acid can form a mixed ligand environment with oxalate ions, reducing the solubility of rare earth complexes and enhancing the precipitation-driven stripping process. Furthermore, under high acidity, impurity ions such as Fe³⁺ are less likely to be extracted from the organic phase into the aqueous phase due to the reverse shift in hydrolysis equilibrium, thereby increasing the purity of the rare earth elements in the stripping solution (aqueous phase).

[0036] Specifically, when the molar ratio of oxalic acid to sulfuric acid is less than 0.5:1, rare earth stripping is incomplete and rare earth remains in the organic phase, resulting in a decrease in rare earth recovery rate; when the molar ratio of oxalic acid to sulfuric acid is greater than 1:1, the concentration of free oxalate ions in the solution is too high, which may form complex salt precipitation with sulfate ions, increasing the acid consumption in the subsequent precipitation process (excess oxalic acid needs to be neutralized) and increasing costs.

[0037] Specifically, an O / A ratio between 2:1 and 1:2 after the co-stripping agent and the organic extract are mixed ensures a positive stripping equilibrium. A high O / A ratio may result in incomplete stripping, requiring additional washing of residual rare earths in the organic phase, increasing regeneration costs. A low O / A ratio may waste the stripping agent.

[0038] S50, sequentially precipitating, washing, filtering and calcining the stripping solution to obtain neodymium oxide.

[0039] Specifically, step S50 further includes: First, excess oxalic acid is added to the stripping solution, and the mixture is stirred at 70-90° C. for 40-80 minutes to obtain neodymium oxalate precipitate.

[0040] Secondly, after washing and filtering the neodymium oxalate precipitate, the neodymium oxalate precipitate is calcined at 700-900° C. and kept warm for 1-3 hours to finally obtain neodymium oxide.

[0041] The technical solution of the present application is now described in further detail with reference to specific embodiments.

[0042] Example 1: See also Figure 2 , Figure 2 This is a process flow chart of a method for recovering neodymium oxide from NdFeB permanent magnets in waste motors provided in Example 1 of the present invention. The specific steps of the method for recovering neodymium oxide from NdFeB permanent magnets in waste motors provided in Example 1 of the present invention are as follows: Step 1: Processing the magnetic steel in the scrap motor: dismantling the scrap motor to remove the magnetic steel, removing the coating and impurities, and cleaning the magnetic steel to obtain clean scrap motor magnetic steel for standby use; Step 2: Place the clean scrap motor magnets in a muffle furnace and bake them at 400°C for 3 hours until the scrap motor magnets are completely demagnetized. Step 3: subjecting the demagnetized waste motor magnetic steel to a first mechanical filtration process to obtain coarse magnetic steel; Step 4: Place the crude magnetic steel in a muffle furnace and calcine at 500°C for 3 hours; Step 5: The calcined coarse magnetic steel is subjected to a second mechanical crushing process to obtain fine-grained magnetic steel, and the fine-grained magnetic steel is sieved through a filter sieve to obtain NdFeB raw material; Step 6: Dissolve the NdFeB raw material in 4 mol / L hydrochloric acid, heat the water bath at 60°C, and dissolve it in the acid while stirring until the NdFeB raw material is completely dissolved in the mixed solution of the NdFeB raw material and hydrochloric acid. Filter the mixed solution to obtain a rare earth solution and iron oxide. Step 7: Extract the rare earth solution with a P204 reagent to obtain an iron-containing raffinate and an organic extract. The iron-containing raffinate can be used to recover a ferric chloride solution with an extraction rate of 95.53%; Step eight, stripping the organic extract containing rare earth elements with a synergistic stripping agent composed of 2 mol / L oxalic acid and 2 mol / L sulfuric acid to obtain a stripping solution containing rare earth elements and a regenerated organic raffinate containing the extractant; wherein the O / A ratio after mixing the synergistic stripping agent and the organic extract is 1:1, and the stripping rate is 99.82%; Step nine, adding excess oxalic acid to the stripping solution, stirring and mixing at a temperature of 80° C. for 60 minutes to obtain neodymium oxalate precipitate; Step 10: After washing and filtering, the neodymium oxalate precipitate is placed in a muffle furnace and calcined at 900° C. for 3 hours to obtain neodymium oxide with a purity of 98.7%.

[0043] Example 2: Embodiment 2 of the present invention provides a method for recovering neodymium oxide using NdFeB permanent magnet materials in waste motors, and the specific steps are as follows: Step 1: Processing the magnetic steel in the scrap motor: dismantling the scrap motor to remove the magnetic steel, removing the coating and impurities, and cleaning the magnetic steel to obtain clean scrap motor magnetic steel for standby use; Step 2: Place the clean scrap motor magnets in a muffle furnace and bake them at 400°C for 3 hours until the scrap motor magnets are completely demagnetized. Step 3: subjecting the demagnetized waste motor magnetic steel to a first mechanical filtration process to obtain coarse magnetic steel; Step 4: Place the crude magnetic steel in a muffle furnace and calcine at 500°C for 3 hours; Step 5: The calcined coarse magnetic steel is subjected to a second mechanical crushing process to obtain fine-grained magnetic steel, and the fine-grained magnetic steel is sieved through a filter sieve to obtain NdFeB raw material; Step 6: Dissolve the NdFeB raw material in 1 mol / L hydrochloric acid, heat the water bath at 80°C, and stir while dissolving the NdFeB raw material in the acid until the NdFeB raw material is completely dissolved in the mixed solution of the NdFeB raw material and the hydrochloric acid. Filter the mixed solution to obtain a rare earth solution and iron oxide. Step 7: Extract the rare earth solution with a P204 reagent to obtain an iron-containing raffinate and an organic extract. The iron-containing raffinate can be used to recover a ferric chloride solution with an extraction rate of 97.25%. Step eight, stripping the organic extract containing rare earth elements with a synergistic stripping agent composed of 1.5 mol / L oxalic acid and 2 mol / L sulfuric acid to obtain a stripping solution containing rare earth elements and a regenerated organic raffinate containing the extractant; wherein the O / A ratio after mixing the synergistic stripping agent and the organic extract is 1:1, and the stripping rate is 97.82%; Step nine, adding excess oxalic acid to the stripping solution, stirring and mixing at a temperature of 80° C. for 60 minutes to obtain neodymium oxalate precipitate; Step 10: After washing and filtering, the neodymium oxalate precipitate is placed in a muffle furnace and calcined at 900° C. for 3 hours to obtain neodymium oxide with a purity of 98.3%.

[0044] Example 3: Embodiment 3 of the present invention provides a method for recovering neodymium oxide using neodymium iron boron permanent magnet materials in waste motors, and the specific steps are as follows: Step 1: Processing the magnetic steel in the scrap motor: dismantling the scrap motor to remove the magnetic steel, removing the coating and impurities, and cleaning the magnetic steel to obtain clean scrap motor magnetic steel for standby use; Step 2: Place the clean scrap motor magnets in a muffle furnace and bake them at 400°C for 3 hours until the scrap motor magnets are completely demagnetized. Step 3: subjecting the demagnetized waste motor magnetic steel to a first mechanical filtration process to obtain coarse magnetic steel; Step 4: Place the crude magnetic steel in a muffle furnace and calcine at 500°C for 3 hours; Step 5: The calcined coarse magnetic steel is subjected to a second mechanical crushing process to obtain fine-grained magnetic steel, and the fine-grained magnetic steel is sieved through a filter sieve to obtain NdFeB raw material; Step 6: Dissolve the NdFeB raw material in 0.5 mol / L hydrochloric acid, heat the water bath at 90°C, and stir while dissolving the NdFeB raw material in the acid until the NdFeB raw material is completely dissolved in the mixed solution of the NdFeB raw material and the hydrochloric acid. Filter the mixed solution to obtain a rare earth solution and iron oxide. Step 7: Extract the rare earth solution with a P204 reagent to obtain an iron-containing raffinate and an organic extract. The iron-containing raffinate can be used to recover a ferric chloride solution with an extraction rate of 97.49%; Step eight, stripping the organic extract containing rare earth elements with a synergistic stripping agent composed of 1 mol / L oxalic acid and 2 mol / L sulfuric acid to obtain a stripping solution containing rare earth elements and a regenerated organic raffinate containing the extractant; wherein the O / A ratio after mixing the synergistic stripping agent and the organic extract is 1:1, and the stripping rate is 96.47%; Step nine, adding excess oxalic acid to the stripping solution, stirring and mixing at a temperature of 80° C. for 60 minutes to obtain neodymium oxalate precipitate; Step 10: After washing and filtering the neodymium oxalate precipitate, it is placed in a muffle furnace and calcined at 900° C. for 3 hours to obtain neodymium oxide with a purity of 99.12%.

[0045] By comparing Examples 1 to 3, it can be seen that when a synergistic stripping agent composed of oxalic acid and sulfuric acid is selected to strip the organic extract containing rare earth elements, neodymium oxide with a purity of ≥98.3% can be obtained; this shows that the synergistic stripping agent significantly improves the metal recovery rate in the NdFeB permanent magnet material, which can reach more than 98%.

[0046] This invention significantly improves the metal recovery rate of NdFeB permanent magnet materials, reaching over 98%, through optimized pretreatment and the use of a synergistic stripping agent for stripping, achieving an O / A ratio between (2:1) and (1:2). Sulfuric acid facilitates organic washing and subsequent recycling, while oxalic acid strips the organic matter to directly form a neodymium oxalate precipitate, reducing leaching costs, simplifying the recovery process, and improving recovery efficiency. This provides favorable conditions for subsequent NdFeB permanent magnet material recovery and is a key step in establishing a recycling industry. This completes the industrial recycling chain and lays a solid foundation for "urban mining."

[0047] In summary, the present invention provides a method for recovering neodymium oxide using NdFeB permanent magnet materials in waste motors, comprising: first, pre-cleaning, roasting and demagnetizing, primary crushing, high-temperature roasting and secondary crushing of the waste motor in sequence, and filtering and screening to obtain NdFeB raw material; secondly, acid-dissolving the NdFeB raw material, and obtaining rare earth solution and iron oxide after solid-liquid separation; then, extracting the rare earth solution to obtain iron-containing raffinate and organic extract; then, stripping the organic extract with a synergistic stripping agent to obtain a stripping solution and a regenerated organic raffinate, the synergistic stripping agent comprising oxalic acid and sulfuric acid; finally, precipitating, washing, filtering and roasting the stripping solution in sequence. The present invention first decomposes the NdFeB permanent magnet material in the waste motor into fine-grained raw materials through a combined process of pre-cleaning → roasting and demagnetization → two crushings → screening, which can increase the contact area of ​​subsequent acid dissolution, simplify the difficulty of subsequent acid dissolution, reduce the amount of acid used and the reaction time, and reduce the acid consumption cost, thereby improving the dissolution efficiency of rare earth elements (such as neodymium); at the same time, the method uses a synergistic stripping agent composed of oxalic acid and sulfuric acid to strip the organic extract, sulfuric acid can help wash the organic phase and then recycle it, and oxalic acid can strip the organic phase to directly form a neodymium oxalate precipitate, thereby reducing the leaching cost of the NdFeB raw material and simplifying the recovery process, and ultimately improving the recovery efficiency of neodymium oxide.

[0048] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0049] The above embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for recovering neodymium oxide from NdFeB permanent magnet materials in waste motors, characterized in that: include: S10, pre-cleaning, roasting and demagnetizing, primary crushing, high-temperature roasting and secondary crushing of the waste motor in sequence, and obtaining NdFeB raw material after filtering and screening; S20, performing an acid dissolution treatment on the NdFeB raw material, and obtaining a rare earth solution and iron oxide after solid-liquid separation; S30, performing an extraction treatment on the rare earth solution to obtain an iron-containing raffinate and an organic extract; S40, stripping the organic extract with a synergistic stripping agent to obtain a stripping solution and a regenerated organic raffinate, wherein the synergistic stripping agent includes oxalic acid and sulfuric acid; S50, sequentially performing precipitation, washing, filtering and roasting on the stripping solution to obtain neodymium oxide.

2. The method for recovering neodymium oxide from NdFeB permanent magnet materials in waste motors according to claim 1, characterized in that: The calcination temperature of the calcination and demagnetization in the step S10 is 300-400° C., and the holding time is 1-3 hours; or the calcination temperature of the calcination and demagnetization in the step S10 is 200-300° C., and the holding time is 10-20 hours.

3. The method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors according to claim 1, characterized in that: In the step S10, the high-temperature calcination temperature is 300-500° C., and the holding time is 2-4 hours.

4. The method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors according to claim 1, characterized in that: In the step S20, the NdFeB raw material is subjected to acid dissolution treatment by water bath heating, and the water bath heating temperature of the water bath heating method is 50-80°C.

5. The method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors according to claim 4, characterized in that: In the step S20, the acid added in the acid dissolution treatment includes at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and the acid concentration is 2-6 mol / L.

6. The method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors according to claim 1, characterized in that: In the step S30, the rare earth solution is extracted with an extractant, and the extractant includes at least one of a P507 reagent, a P204 reagent, a TBP reagent, and a C272 reagent.

7. The method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors according to claim 1, characterized in that: In the step S40, the molar ratio of oxalic acid to sulfuric acid in the synergistic stripping agent is (0.5-1):

1.

8. The method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors according to claim 1, characterized in that: In the step S40, the O / A ratio of the synergistic stripping agent and the organic extract after mixing is between 2:1 and 1:

2.

9. The method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors according to claim 1, characterized in that: In the step S50, the step of performing precipitation treatment on the stripping solution includes: adding excess oxalic acid to the stripping solution, mixing and stirring at 70-90° C. for 40-80 minutes to obtain neodymium oxalate precipitate.

10. The method for recovering neodymium oxide by utilizing NdFeB permanent magnet materials in waste motors according to claim 9, characterized in that: In the step S50, the step of calcining the neodymium oxalate precipitate includes calcining the neodymium oxalate precipitate at 700-900° C. and keeping the temperature for 1-3 hours.

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